Society for Conservation Biology 16th Annual Meeting July 14-July 19 2002
co-hosted by DICE and the British Ecological Society


Abstracts for Conservation Genetics
Session Two

Tuesday 16th July, 10.15 - 12.15, Cornwallis Lecture Theatre 1

Chair: Jonathan Ballou



Conference Home Page | Session timetable


(BLOCK CAPITALS indicate the presenting author)

10.15 - 10.30
PEACOCK, MARY M. Biological Resources Research Center, Department of Biology, University of Nevada, Reno, Nevada 89557, USA, <mpeacock@unr.nevada.edu>.

POPULATION-LEVEL PHYLOGENETIC ANALYSIS OF A THREATENED SALMONID AND THE "EVOLUTIONARILY SIGNIFICANT UNIT" CONCEPT

The Lahontan cutthroat trout, Oncorhynchus clarki henshawi, a threatened species under the Endangered Species Act, is the only endemic trout in the Lahontan basin (northern Nevada, western California and southern Oregon) in western North American. Over 90 percent of the populations have been lost in the eastern river-dominated basin and 95 percent in the western lake-dominated basin. Threats to this species include habitat loss and degradation, and competition and hybridisation with non-native salmonids. Previous genetic work using allozyme and mitochondrial DNA suggest that there are three Evolutionarily Significant Units (ESUs) within the range of this species. However, low levels of genetic variability in these markers precluded a population level analysis within ESUs. Eleven species-specific microsatellite loci were used to construct a population-level phylogeny for populations from subbasins within each ESU. Results of microsatellite analysis support the original three ESU designation and further distinguishes genetically distinct subbasins within each ESU. Distinct subbasins are supported by statistically significant FST values ranging from 0.211-0.467. FST values between Lahontan cutthroat trout and other cutthroat subspecies range from 0.410-0.677. The high FST values between populations among subbasins within current ESU designation suggests that recovery activities should focus at the subbasin level.


10.30 - 10.45
NEVILLE ARSENAULT, HELEN, and Mary Peacock. Ecology, Evolution, and Conservation Biology, University of Nevada, Reno, NV, 89557, USA, <hneville@unr.nevada.edu> (HNA), Biological Resources Research Center, University of Nevada, Reno, NV 89557, USA (MP).

GENETIC ASSESSMENT OF COMPLEX DYNAMICS IN AN INTERIOR BASIN SALMONID METAPOPULATION

The complex dispersal behaviour and habitat use associated with salmonids make predicting their population genetic structure difficult. Empirical data from natural populations that both improve our understanding of processes shaping genetic structure, and aid in paramaterisation of predictive models are sorely needed. In a study of the threatened Lahontan cutthroat trout, Oncorhynchus clarki henshawi, in an interconnected stream system in Nevada, we used 11 microsatellite loci to assess: 1) the congruence of genetic structure with habitat spatial structure, 2) the existence of resident and migratory individuals in the system, 3) the influence of body size on dispersal behaviour, and 4) the influence of habitat quality on levels of connectedness and population persistence. Overall, a substantial degree of differentiation was detected at a very small geographic scale. Patterns of differentiation among samples indicate that population structure is influenced not by habitat spatial structure alone, but also potentially by the existence of different life-history strategies in the system. Surprisingly, preliminary analyses suggest that body size is not a good predictor of dispersal behaviour, but that habitat quality and connectivity influence the likelihood of dispersal. Finally, while population bottlenecks were detected, their locations did not match our predictions based on habitat characteristics.



10.45 - 11.00
LUDWIG, ARNE and Patrick Williot. Institute of Zoo Biology and Wildlife Research, Alfred-Kowalke-Str. 17, 10315 Berlin, Germany, <ludwig@izw-berlin.de> (AL) and Cemagref, Division Aquaculture et Pêche, BP 3, 33612 Cestas, France (PW).

GENETIC ASPECTS OF CONSERVATION OF THE COMMON STURGEON ACIPENSER STURIO

The Common sturgeon, Acipenser sturio, listed in Appendix I of CITES, is one of the most threatened freshwater fish species worldwide. Historically, this species inhabited nearly all large tributaries of the European Atlantic, the Black, Adriatic, Mediterranean and North seas. A. sturio - formerly the widest distributed sturgeon species in Europe - currently reproduces only in the Gironde basin, France. Three single natural reproductions were observed since 1980. The survival of this species depends on successful artificial reproduction and stocking. For this reason, most of the juveniles, semi-adult and adult males and females caught during the last decade were taken from the river and reared in ponds. Our aim is to develop a breeding plan for conservation of genetic variability as still present. Therefore, we analysed the genetic structure using microsatellites and a sequence fragment of the highly variable mitochondrial D-loop of both the natural population and the broodstock. In general, genetic variability is very low. All specimens shared the same mitochondrial haplotype, and heterozygosity was very low compared with its North American sister species, A. oxyrinchus. However, our microsatellite data also show a sub-structuring. Specimens representing largest genetic distances should be used for artificial reproduction first.



11.00 - 11.15
PEARMAN, PETER B., Trenton W. J. Garner, and Sonia Angelone. Zoological Institute, University of Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland, <pearman@zool.unizh.ch>.

GENETIC DEPLETION IN RANA LATASTEI POPULATIONS: MECHANISMS AND PROVISIONAL RECOMMENDATIONS

Rana latastei is listed by the IUCN as a ‘nearly threatened’ species, although this frog is one of Europe’s most endangered amphibians. We used a genetic approach to determine whether certain populations should be given priority for conservation. We initially employed primers for seven microsatellite loci and analysed samples from twelve Swiss populations and seven Italian populations. The Swiss populations are depleted in genetic variation compared to their Italian counterparts. We then conducted extended sampling from twelve additional Italian populations, evenly distributed throughout the species’ range, in order to test whether range-peripheral populations show genetic depletion in general. While the results are equivocal on the status of peripheral populations, there is a strong east-west gradient in genetic variability, suggesting the potential vulnerability of western populations to extinction. Post-Pleistocene range expansion is a potential mechanism. Additional data suggest that interactions with a widespread congener and habitat destruction may also contribute to this pattern. Loss of western populations would constitute a major range contraction for R. latastei. We recommend that conservation activities provisionally focus on preserving preferred bottomland forest habitat and on improving corridors for dispersal in the western portion of the species’ range. Patterns of adaptive variation may suggest additional priorities.



11.15 - 11.30
BURNS, EMMA L., and Bronwyn A. Houlden. School of Biological, Earth and Environmental Sciences, University of New South Wales, 2052, Sydney, Australia, <e.burns@student.unsw.edu.au>.

GENETIC DIVERSITY AND DIFFERENTIATION ASSESSED AMONG GREEN AND GOLDEN BELL FROG POPULATIONS

Green and Golden Bell Frogs, Litoria aurea, were once one of Australia’s more common Hylids. However, like many amphibian species worldwide, it has undergone dramatic population declines resulting in a listing of endangered in NSW under the Threatened Species Conservation Act, 1995. Although the species still persists throughout the majority of its historical range, remaining populations are mostly small and fragmented. We undertook an empirical assessment of genetic structure and diversity to guide management strategies for preserving diversity. Using microsatellite markers we assessed levels of genetic variation within and between 23 populations and found heterozygosity levels ranged from 0.43 - 0.79. Despite the recent population history we found no populations displayed a genetic signature indicative of a recent bottleneck, suggesting populations declines have not been severe enough to be detected and/or that gene flow has been sufficient to ameliorate effects. Furthermore we found weak population structure among many populations using MDS but over all differentiation was significant (FST = 0.17, P < 0.001), and no isolation-by-distance pattern was evident. Results indicate that effective management should ensure species survival. Crucial to this is the maintenance of habitat corridors to allow current migration; further isolation of remaining populations could have dire impacts.



11.30 - 11.45
Túnez, JI , D Centrón, ML Guichón, MH CASSINI. Departamento de Ciencias Básicas, Universidad Nacional de Luján & Departamento de Microbiología, Universidad de Buenos Aires, Argentina. mcassini@mail.unlu.edu.ar

GENETIC CONSEQUENCES OF HUNTING IN ARGENTINEAN COYPUS

In the South Cone of South America, coypu Myocastor coypus is top ranked in the wildlife furbearer trade and requires management actions to attain sustainable exploitation. In its wide exotic distribution, coypu is frequently considered a pest that attacks crops and hazards native flora and fauna. We conduct a long term project on the ecology and behaviour of coypu in Argentina. Here, we present preliminary evidence on the genetic consequences of hunting pressure on natural populations. We have previously found that populations under high hunting pressure are small and composed mainly by immigrants (see Poster by Guichón and Cassini). We developed the molecular technique RAPD to obtain parameters of the genetic structure of populations with different degrees of hunting pressure. We found (1) a positive relation between genetic distance and geographic location, (2) a positive relation between genetic variability and population size (therefore, negative with hunting pressure), and (3) that genetic variability between immigrants was less than between residents. We concluded that hunting reduces genetic variability that cannot be compensated by immigration because immigrants are genetically related.



11.45 - 12.00
Matocq, Marjorie, Dale McCullough, JONATHAN BALLOU, and Karen Jones. Department of Conservation Biology, Conservation and Research Center, Smithsonian National Zoological Park, Smithsonian Institution, Washington D.C. 20008, USA (MM); Ecosystem Sciences Division, Department of Environmental Science, Policy, and Management, University of California, Berkeley, CA 94720, USA (DM), Department of Conservation Biology, Conservation and Research Center, Smithsonian National Zoological Park, Smithsonian Institution, Washington D.C. 20008, USA, <ballouj@nzp.si.edu> (JB); and California Department of Fish and Game, Wildlife Investigations Laboratory, Rancho Cordova, CA 95670, USA (KJ).

FOUNDER EVENTS, BOTTLENECKS AND GENETIC DIVERSITY IN THE TULE ELK: THEORETICAL PREDICTIONS MEET REALITY

The California tule elk, Cervus elaphus nannodes, was reduced to fewer than five individuals in the 1800s. Since then, the population has recovered to over 3000 individuals and has been translocated to 22 subpopulations throughout its historic range. Previous models that simulated genetic drift associated with the initial bottleneck, subsequent founding events, and small translocated population sizes predicted substantial losses of genetic diversity in this system. Here we measure genetic diversity at four nuclear microsatellite loci in tule elk, Roosevelt (C. e. roosevelti) and Rocky Mountain elk (C. e. nelsoni) and show that tule elk have significantly less genetic diversity than the other elk subspecies. Using the diversity of Roosevelt and Rocky Mountain elk as a baseline against which to measure change, we show that actual loss of diversity in tule elk is highly correlated with the loss predicted by theory. In addition to this subspecies-wide correlation, the bottleneck theory also accurately predicted loss of diversity within most individual subpopulations of tule elk. This study shows that loss of genetic diversity of tule elk can be explained by the species’ historical demography and that theoretical predictions can be used to explore effects of demographic history on a population’s genetic characteristics.



12.00 - 12.15
RODRIGUEZ-CLARK, KATHRYN M. Department of Ecology and Evolutionary Biology, Princeton University, Princeton, NJ 08544, USA, <kate@sigmaxi.org>.

CAPTURING ADAPTIVE GENETIC VARIATION FROM THE WILD: IS A SMALL NUMBER OF FOUNDERS ENOUGH?

It is well-established that even ten pairs of founders will carry a large proportion of neutral molecular genetic diversity (heterozygosity) from nature to captivity – however, will the captured population also retain the same ability to respond to natural selection as the original wild one (as is conventionally assumed)? Simple as this question may seem, to date it has not been directly addressed. Using methods borrowed from quantitative genetics to examine populations of Oncopeltus fasciatus derived from 50 pairs of wild founders, I estimate variance components for five traits both in nature and in captivity. Results indicate that while additive genetic variance and evolvability remain close to their wild levels for three morphological traits, there is evidence for unexpected declines in two life-history traits, despite the large number of founders. This may be due to differing genetic structures or interactions with environmental factors. Thus, caution may be warranted in the assumption that a small number of founders will bring the full range of adaptive genetic variation from the wild to captivity for all traits. Techniques presented can be extended to captive-bred populations of endangered species, and appear preferable to simply monitoring heritability, which has been suggested in the past.

The SCB2002 pages are maintained by Christine Eagle
email: C.M.Eagle@ukc.ac.uk
Conference email: scb2002@ukc.ac.uk
Last updated: 30.06.02